The worst-performing technology appears to come from open source projects like SpamPal and SpamAssassin, which fully satisfy just 16 percent of users.
The most-satisfied customers use challenge-response vendors, which fully satisfied users 67 percent of the time.
Challenge-response tools allow messages from known senders without interruption, since virtually all spam comes from first-time senders. First-time senders are challenged with a reply email telling them to reply, click on a URL, or visit a website to complete delivery of the message.
"This procedure overcomes the weakness of spammers since spammers never monitor the reply-to accounts of their messages."
Tongkrongan BMX Garry
